Rechargeable batteries may require some form of battery charging system. Battery charging systems transfer power from an energy source, such as household AC power, into the energy storage (e.g., the battery). The recharging process in a battery generally includes regulating voltages and currents from the power source with a charger, so that the voltages and currents supplied to the power storage meet the particular power storage's charging specifications. For example, if the voltages or currents supplied to a battery are too large, the battery can be stressed or damaged. On the other hand, if the voltages or currents supplied to a battery are too small, the charging process can be slow and inefficient. Additionally, if the charging process is not carried out efficiently, the battery's capacity may not be optimally used and its useful lifetime (the number of charge/discharge cycles available) may be reduced.